Narrative:The Astra jet departed Coatesville (CTH) at 15:20 for DeKalb-Peachtree (PDK). They were scheduled to spend the night in the Atlanta area, and then continue the next morning to a private airstrip in Texas. Though rain was forecast for the Atlanta area, "it was well within limits."Upon arrival in the Atlanta area they were vectored for the ILS runway 20L approach. The weather was above minimums with 1 3/4 miles visibility in heavy rain. The captain was in the right seat and monitored the approach as the non-flying pilot. The first officer was in the left seat and was the flying pilot. The first officer had selected the autopilot on previously, and after capturing the ILS the airplane began to descend on the glideslope. The captain then announced that the approach lights were in sight and the first officer responded that he also had the approach lights in sight, and turned off the autopilot.The first officer then attempted to continue and land visually, though they were flying in moderate to heavy rain. Up to this point they had experienced no turbulence and had "good visual contact" with the approach lights. The first officer then turned on the windshield wipers and approximately 10-seconds after, lost visual contact with the runway. He announced that he had lost visual contact, but the captain stated that he still had the runway in sight. The first officer then considered a missed approach but continued, because the captain still had "good visual contact." The captain told the first officer, "I have the lights" and began to direct the first officer. He then, however, "took over the controls" and as they touched down, the speed brakes extended, and they realized that they had approximately 1,000 feet of runway remaining. The tower then advised them "to go around." The airplane then overran the runway, struck thelocalizer antenna and stopped near the airport fence after traveling several hundred feet past the end of the runway.The airplane received impact damage to the nose, wings, engines, and landing gear and six of the ILS localizer's antenna had received impact damage.

PROBABLE CAUSE: "The pilot's failure to initiate a missed approach and his failure to obtain the proper touchdown point while landing in the rain. Contributing to the accident were the operator's lack of standard operating procedures and the inadequate maintenance of the windshield."